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Nanoco Technologies Ltd. (Nanoco) is a UK-based nanotechnology company that spun out from the research group of Prof. Paul O’Brien at the University of Manchester in 2001. The company's development has been driven by Dr Nigel Pickett, Nanoco's Chief Technology Officer, whose pioneering work on the patented "molecular seeding" process has formed the basis of Nanoco's unique technology, and Dr Michael Edelman, who joined Nanoco as CEO in 2004, leading the company's growth from a two-man start-up to a publicly traded organisation with more than 120 employees across the globe. Since 2004, Nanoco has focussed its research efforts into the development of quantum dots and other nanoparticles that are entirely free of cadmium and other regulated heavy metals. Nanoco has licensed its technology to Dow,[1] Wah Hong,[2] and Merck.[3]

Nanoco's head office is in Manchester, UK. The company also has a production facility in Runcorn, UK, a US subsidiary in Concord, Massachusetts, and business development offices in Japan, Korea and Taiwan.

Nanoco Technologies is unique in the nanomaterials market as a company that manufactures large quantities of quantum dots (QDs), in particular cadmium-free quantum dots.[4]

Market Diffusion

Growing industrial adoption of quantum dot technology by R&D and blue-chip organisations has led to a greater demand for the bulk manufacture of the product.[5] The bulk manufacture of quantum dots provides companies with the platform to develop a wide variety of next-generation products, particularly in application areas such as displays (Quantum dot display), LED lighting, backlighting, flexible low-cost solar cells and biological Imaging.

In January 2013, Nanoco announced a licensing deal with the Dow Chemical Company.[6] Following commissioning of Dow's plant in Cheonan, South Korea, Nanoco received its first royalty payment in 2016.[7] Nanoco has signed further licensing agreements with Wah Hong[8] and Merck.[9] At the Consumer Electronics Show 2015, improved backlighting using QDs in LCD television sets was a major topic. South Korean (Samsung, LG), Chinese (TCL, Hisense, Changhong) and Japanese (Sony) TV manufacturers had such TVs on display.[10]

From May 2009 the company has been listed on AIM at the London Stock Exchange [1], but in May 2015 it moved to the main London Stock Exchange market.

Cadmium-Free Quantum Dots

There is a move towards legislation that restricts or prohibits the use of heavy metals in products such electrical and electronic equipment. In Europe, the restricted metals include cadmium, mercury, lead and hexavalent chromium.[11] Cadmium is restricted 10-fold more than the other heavy metals, to 0.01% or 100 ppm by weight of homogeneous material. There are similar regulations in place, or soon to be implemented, worldwide including in Norway, Switzerland, China, Japan, South Korea and California.

Cadmium and other restricted heavy metals used in conventional quantum dots are of a major concern in commercial applications. For QDs to be commercially viable in many applications they must not contain cadmium or other restricted elements. Nanoco has developed a range of CFQD® quantum dots, free of any regulated heavy metals.[12] These materials show bright emission in the visible and near-infra-red region of the spectrum.

Nanoco has developed a patented "molecular seeding" method of QD synthesis.[13] Unlike "high temperature dual injection" methods of QD synthesis, the molecular seeding method circumvents the need for a high temperature injection step by utilising molecules of a molecular cluster compound to act as nucleation sites for nanoparticle growth. To maintain particle growth, further precursor additions are made at moderate temperatures until the desired QD size is reached. The process can easily be scaled to large volumes, and is used to produce Nanoco's CFQD® heavy metal-free quantum dots.

Lighting

The white light LED market is hugely important, with the promise of increased lamp lifetimes and efficiencies paving the way for a revolution in the lighting industry.[14] Colour rendering and efficiency are the two most important criteria for traditional light sources for general lighting. The ability of a light source to illuminate an object's true colour is denoted by its colour rendering index. For example, sodium lamp street lighting has poor colour rendering capability as it's difficult to distinguish a red car from a yellow car.

Current white light LED technology utilises a cerium doped YAG:Ce (yttrium aluminium garnet) down-conversion phosphor pumped by a blue (450 nm) LED chip. The combination of blue light from the LED and a broad yellow emission from the YAG phosphor results in white light. Unfortunately, this white light often appears somewhat blue and is often described as "cold" or "cool" white. Quantum dots can be used as LED down-conversion phosphors because they exhibit a broad excitation spectrum and high quantum efficiencies. Furthermore, the wavelength of the emission can be tuned completely across the visible region simply by varying the size of the dot or the type of semiconductor material. As such, they have the potential to be used to generate virtually any colour and, more importantly, warm whites strongly desired by the lighting industry.

Additionally, by using a combination of one to three different types of dots with emission wavelengths corresponding to green, yellow, and red it is possible to achieve white lights of different colour rendering indexes. Because of these attractive features, QD-LEDs[15] are beginning to receive attention from both industrial and academic researchers. In addition to white lighting for general illumination, there are other opportunities for QD-LEDs. For example, green LEDs are not particularly efficient, thus green-emitting QDs on top of an efficient blue LED chip may be a solution. Similarly, amber LEDs suffer from temperature dependencies and thus a QD solution may be applicable. Furthermore, because of the widely tunable QD emission, it's possible to have near UV-pumped QD-LEDs with combinations of QDs which emit virtually any color on the chromaticity diagram. This could have important applications in signage by, for example, replacing neon bulbs.

Displays

In recent years, liquid crystal display (LCD) technology has dominated the electronic display device market, with applications ranging from smartphones, to tablets, to televisions. Continual improvements in display quality and performance are sought. The backlighting technology in conventional LCD screens currently uses white LEDs. One of the shortcomings of this technology is that the white LEDs provide insufficient emission in the green and red areas of the visible spectrum, limiting the range of colours that can be displayed. One solution is to integrate QDs into LCD backlight units to improve the colour quality.[16] Green and red QDs can be used in combination with blue LED backlights; the blue light excites the QDs, which convert some of the light into highly pure green and red light to expand the range of colours that the LCD screen can display.

Biological Imaging

Over the years, techniques have been developed for medical imaging using fluorescent dyes, as a powerful tool for the diagnosis and treatment of diseases. However, the fluorescent dyes currently used offer poor photostability, with narrow absorption spectra (requiring excitation at a precise wavelength) and/or weak fluorescence due to low extinction coefficients. The development of fluorescence imaging agents using QDs may pave the way for new medical imaging techniques.[17] QDs offer a number of advantageous properties for fluorescence imaging, including high photostability, broad absorption spectra, narrow, symmetric and tunable emission spectra, slow excited state decay rates and high extinction coefficient resulting in strong fluorescence.[18]

CIGS/CIS Nanoparticles

Fabrication of current thin film solar cell technology involves costly evaporation techniques, which is hindering their mass market adoption. CIGS and CIS (copper indium gallium diselenide, copper indium diselenide) nanocrystals or quantum dots allow the use of conventional, low cost printing techniques to fabricate thin film solar cells.[19]

Using a colloidal method to make CIGS and CIS nanoparticles for photovoltaic applications provide materials that possess the desired elemental ratios or stoichiometry, which can be adjusted to meet specific needs. The nanoparticles are passivated with organic capping agents, providing solubility and thus solution processability.

In this way, the material can be printed onto a substrate using a wide range of printing techniques, even in roll-to-roll processes. Once printed, the CIGS/CIS materials are heated to remove the organic capping agent, which destroys the quantum confinement associated with the nanoparticles and provides for a p-type semiconductor film possessing the desired crystalline structure.

References

  1. ^ http://www.nanocotechnologies.com/media/press-releases/dow-sell-market-and-manufacture-cadmium-free-quantum-dots-lcd-displays
  2. ^ http://www.nanocotechnologies.com/media/press-releases/commercialisation-agreement-display
  3. ^ http://www.nanocotechnologies.com/media/press-releases/nanoco-and-merck-sign-agreement
  4. ^ Nanoco - year of progress, "University of Manchester", accessed 22 March 2010
  5. ^ Who we are and what we do..., "Nanoco", Website Reference, Accessed 26 March 2010
  6. ^ http://www.nanocotechnologies.com/media/press-releases/dow-sell-market-and-manufacture-cadmium-free-quantum-dots-lcd-displays
  7. ^ http://www.nanocotechnologies.com/media/press-releases/first-royalty-payment-display-market
  8. ^ http://www.nanocotechnologies.com/media/press-releases/commercialisation-agreement-display
  9. ^ http://www.nanocotechnologies.com/media/press-releases/nanoco-and-merck-sign-agreement
  10. ^ CES 2015 - Placing bets on the New TV Technologies. IEEE Spectrum, 7 January 2015. Retrieved 12 January 2015
  11. ^ Directive 2002/95/EC
  12. ^ http://www.nanocotechnologies.com/what-we-do/products/cadmium-free-quantum-dots
  13. ^ I. Mushtaq, S. Daniels and N. Pickett, Preparation of Nanoparticle Material. US Patent 7,588,828, 15 September 2009
  14. ^ A quantum leap for lighting, "The Economist", print edition 4 Mar 2010.
  15. ^ Nigel L. Pickett, Ombretta Masala, James Harris: "Material Matters" 3.1, page 24. 2007.
  16. ^ http://www.nanocotechnologies.com/what-we-do/applications/displays
  17. ^ http://www.nanocotechnologies.com/what-we-do/applications/biological-imaging
  18. ^ S.B. Rizvi, M. Keshtgar and A.M. Seifalian. Quantum Dots: Basics to Biological Applications. In Handbook of Nanophysics: Nanomedicing and Nanorobotics; K. D. Sattler; Ed.; CRC Press; Boca Raton, Florida, 2010; p. 1.2
  19. ^ Duncan Graham-Rowe: From dots to devices, "Nature Photonics" 3, 307–309 (1 June 2009).
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